Comment 34 for bug 1332900

you have to post the output of alsa-info.sh

try hdajackretask to change of the remaining nodes (e.g. 0x1a) to speaker with same default assoc and higher sequence number

find out which headphones is headset and headphone

most likely the headset mic is similar to dell-headset-multi but alienware don't need headphone mic since it has a mic jack

the easy way is to disable one headphone jack so that the driver can create volume controls for the speaker, subwoofer and headphone since alc668 only have three volume control

you need lfe filter which is available in pulseaudio 7.0

http://cgit.freedesktop.org/pulseaudio/pulseaudio/log/?qt=grep&q=lfe+filter